British Rail Class D20/2

The British Railways Class D20/2 diesel-hydraulic locomotives were built by the North British Locomotive Company in Glasgow during 1957 and 1958. Although never assigned a TOPS class as they were withdrawn before TOPS was introduced British Loco enthusiasts coined the term "Class 41". All were named after Royal Navy vessels, hence the nameplates each bore a subtitle "Warship Class".

British Rail Class D20/2
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'Warship' Diesel-hydraulic at Reading (General) on an Up express.
Power type	Diesel-hydraulic
Builder	North British Locomotive Company
Serial number	27660–27664
Build date	1958–1959
Total production	5
Configuration	A1A-A1A
UIC classification	(A1A)'(A1A)'
Gauge
Wheel diameter	Driving: 3 ft 7 in (1.092 m) Idling:
Wheelbase	50 ft 0 in (15.24 m)
Length	65 ft 0 in (19.81 m)
Width	8 ft 8 in (2.64 m)
Height	12 ft 10 in (3.91 m)
Locomotive weight
Fuel capacity	800 imp gal (3,600 l; 960 US gal)
Prime mover	NBL-MAN L12V 18/21S, 2 off
Transmission	Hydraulic, Voith L306r
Multiple working	■ Orange Square
Top speed	90 mph (145 km/h)
Power output	Engines: 1,000 bhp (746 kW) × 2
Tractive effort	Maximum: Continuous:
Train heating	Steam
Locomotive brakeforce
Train brakes	Vacuum
Career	British Railways
Number	D600–D604
Nicknames	“Warships”
Axle load class	Route availability
Retired	December 1967
Disposition	All scrapped

British Rail Class D20/2 Media

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  The nameplate of D601 Ark Royal on display at the National Railway Museum. These were generally coloured red, but this was changed to black if the locomotive was repainted blue.